Low back pain: what determines functional outcome at six months? An observational study.

Background: The rise in disability due to back pain has been exponential with escalating medical and societal costs. The relative contribution of individual prognostic indicators to the pattern of recovery remains unclear. The objective of this study was to determine the prognostic value of demographic, psychosocial, employment and clinical factors on outcome in patients with low back pain

Methods: A prospective cohort study with six-month follow-up was undertaken at a multidisciplinary back pain clinic in central London employing physiotherapists, osteopaths, clinical psychologists and physicians, receiving referrals from 123 general practitioners. Over a twelve-month period, 593 consecutive patients referred from general practice with simple low back pain were recruited. A baseline questionnaire was developed to elicit information on potential prognostic variables. The primary outcome measures were change in 24-item Roland Morris disability questionnaire score at six months as a measure of low back related functional disability and the physical functioning scale of the SF-36, adjusted for baseline scores.

Results: Roland Morris scores improved by 3.8 index points (95% confidence interval 3.23 to 4.32) at six months and SF-36 physical functioning score by 10.7 points (95% confidence interval 8.36 to 12.95). Ten factors were linked to outcome yet in a multiple regression model only two remained predictive. Those with episodic rather than continuous pain were more likely to have recovered at six months (odds ratio 2.64 confidence interval 1.25 to 5.60), while those that classified themselves as non-white were less likely to have recovered (0.41 confidence interval 0.18 to 0.96).

Conclusions: Analysis controlling for confounding variables, demonstrated that participants showed greater improvement if their episodes of pain during the previous year were short-lived while those with Middle Eastern, North African and Chinese ethnicity demonstrated minimal improvement. The study did not support previous findings that a wide range of factors could predict outcome.